Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 ae90fe62432ec32b…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:30:29 Authoring application: Microsoft Excel
MD5: fe7c71ae315b511460bf6562424fcfd7 SHA-1: 2f31ec3a5d5b76f58f3709c33e032e379ca20f9f SHA-256: ae90fe62432ec32b5329380274cfc05b451c5aa8422360119687b5c884bb8ec8
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that utilizes dangerous functions, specifically the RUN function. This strongly suggests the macro is designed to execute arbitrary commands. While no specific URLs or hashes were extracted, the presence of the Auto_Open macro implies a downloader or initial execution stage for a more complex attack. The macro sheet itself is named 'yOlMPzpKUQ', which might be a weak indicator.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
ac3d03fce84d2ec080c82eac212264eedee6ecff3862f3f70dfa4a3293356c26		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6642 bytes

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